Stability and diffraction features of quasicrystal and 2/1 approximant phase in an Au42In42Yb16 alloy

An Au42In42Yb16 alloy has been studied by transmission electron microscopy in as-cast and melt-spun conditions. The as-cast alloy was found to contain a cubic 2/1 approximant phase (along with another crystalline phase) with lattice parameter 2.46nm and space group Pa3-bar. Electron diffraction features of this phase have been described. An icosahedral quasicrystal formed on melt-spinning. Differential thermal analysis indicates that the quasicrystalline phase is stable above 525 deg. C, until melting. Annealing at temperature 550 deg. C improves the quality of the quasicrystal, while annealing at 450 deg. C shows transformation to a microcrystalline state. At both temperatures, a 1/1 cubic approximant phase separates out